﻿#include "Date.h"
Date::Date(int year, int month, int day)
{
	if (month > 0 && month < 13 && day > 0
		&& day <= GetMonthDay(year, month))
	{
		_year = year;
		_month = month;
		_day = day;
	}
	else
	{
		cout << "非法日期" << endl;
		assert(false);
	}

}

Date::Date(const Date& d)//拷贝构造函数
{
	_year = d._year;
	_month = d._month;
	_day = d._day;
}
bool Date::operator<(const Date& x)const
{
	if (_year < x._year)
	{
		return true;
	}
	else if (_year == x._year && _month < x._month)
	{
		return true;
	}
	else if (_year == x._year && _month == x._month && _day < x._day)
	{
		return true;
	}
	return false;
}

bool Date::operator==(const Date& x)const
{
	return _year == x._year && _month == x._month && _day == x._day;
}

bool Date::operator<=(const Date& x)const
{
	return *this == x || *this < x;
}

bool Date::operator>(const Date& x)const
{
	return !(*this <= x);
}

bool Date::operator>=(const Date& x)const
{
	return !(*this < x);
}

bool Date::operator!=(const Date& x)const
{
	return !(*this == x);
}

int Date::GetMonthDay(int year, int month)
{
	static int daysArr[13] = { 0,31,28,31,30,31,30,31,31,30,31,30,31 };
	if (month == 2 && ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)))
	{
		return 29;
	}
	else
	{
		return daysArr[month];
	}
}

Date& Date::operator+=(int day)//这里修改了原对象，是+=的逻辑，不是纯+
{
	if (day < 0)
	{
		return *this -= abs(day);
	}
	_day += day;
	while (_day > GetMonthDay(_year, _month))
	{
		_day -= GetMonthDay(_year, _month);
		++_month;
		if (_month == 13)
		{
			++_year;
			_month = 1;
		}
	}
	return *this;
}

Date Date::operator+(int day)const//可以使用+=来复用
{
	Date tmp(*this);
	tmp += day;
	return tmp;
}

Date& Date::operator++()//前置++
{
	*this += 1;
	return *this;
}

Date Date::operator++(int)//后置++
{
	Date tmp = *this;
	*this += 1;
	return tmp;
}

Date& Date::operator-=(int day)
{
	if (day < 0)
	{
		return *this += abs(day);
	}
	_day -= day;
	while (_day <= 0)
	{
		--_month;
		if (_month == 0)
		{
			_month = 12;
			_year--;
		}
		_day += GetMonthDay(_year, _month);
	}
	return *this;
}

Date Date::operator-(int day)const
{
	Date tmp(*this);
	tmp -= day;
	return tmp;
}

Date& Date::operator--()//前置--
{
	*this -= 1;
	return *this;
}

Date Date::operator--(int)//后置--
{
	Date tmp = *this;
	*this -= 1;
	return tmp;
}

int Date::operator-(const Date& d)
{
	Date max = *this;
	Date min = d;
	int flag = 1;

	if (max < min)
	{
		max = d;
		min = *this;
		flag = -1;
	}

	int n = 0;
	while (min != max)
	{
		min++;
		n++;
	}
	return n * flag;
}

ostream& operator<<(ostream& out, const Date& d)
{
	out << d._year << "-" << d._month << "-" << d._day << endl;
	return out;
}

istream& operator>>(istream& in, Date& d)
{
	int year, month, day;
	in >> year >> month >> day;
	if (month > 0 && month < 13 && day > 0
		&& day <= Date::GetMonthDay(year, month))
	{
		d._year = year;
		d._month = month;
		d._day = day;
	}
	else
	{
		cout << "非法日期" << endl;
		assert(false);
	}
	return in;
}

